Post some pictures of your ride.

There are different upgrade theories from keeping 100% original, to fixing what breaks, to stripping to a bare frame, and installing all new/modern components.

Personally, I'd keep what you have, tune up the bike, and start riding it. Perhaps over time you'll decide to make some changes. Perhaps gearing changes????

Shoes and Pedals?

Water bottles?

Pumps?

Never count on the grease in an old bike being good. Never hurts to repack all the bearings, wheels, bottom bracket, headset, jockey wheels, etc. It also helps familiarize yourself with your bike.